The invention also relates to a cutting element for a routing tool.
Such a routing tool and a cutting element which can be used therewith is known, for example, from EP 0 861 144 B1 or U.S. Pat. No. 6,659,694 B1.
In the known tools, individual cutting elements are fastened in a recess tangentially to the lateral surface of the supporting body by a central screw, said recess being embodied in such a way that the cutting element bears with its outer edges (circumferential wall) against three locations in the recess and is supported against the applied cutting forces. The individual cutting elements are arranged in such a way that they form a continuous cutting helix in the tool supporting body.
In order to be able to fasten the edge blades at a shear cut angle relative to the tool center plane, the supporting body must be formed beyond the blade region of the cutting element so that there is sufficient construction space for the recess for accommodating the edge cutting element. Because the cutting elements are to be positioned in their associated recesses in such a way that they are supported against applied cutting forces, the supporting body must consequently enclose the edge cutting elements, that is to say it must extend beyond the cutting element. In order to achieve high true-running accuracy and exact alignment of the adjacent cutting elements in a continuous helix, the outer edges of the cutting elements (bearing surfaces) must be ground in a highly precise manner or the cutting edges in their entirety must be ground continuously in the fitted state of the cutting elements in the supporting body.
Disclosed in the journal “HOB 05/2008, page 72” is a routing tool having a light alloy supporting body in which the cutting elements are likewise screwed in a substantially radial direction via a central hole. Here, too, the cutting elements are positioned in a recess which orients the cutting element laterally at an outer edge. The routing tool has cutting elements with shear cut angles which produce a shearing cut toward the tool center plane. In order to be able to position the cutting elements as close to the edge of the supporting body as possible, the cutting elements are not of symmetrical construction, but rather a distinction is made between “right-hand” and “left-hand” cutting elements. The supporting body encloses the edge cutting elements on the outer side. The tool width is thus substantially greater than the actual cutting width which can be realized with the tool. The cutting elements are supported against the cutting forces solely by frictional forces of the screw preloading. In the region of the blades, the supporting body has no chip spaces for receiving the cut material. So that the individual blades are not reflected as marks on the workpiece, the cutting edges must be finish-ground in the fitted state.
It has proved to be advantageous for the tool supporting body of such routing tools to be, if possible, of cylindrical design, in order to achieve a low-noise configuration, and in addition to allow the blades to project only slightly beyond the lateral surface of the supporting body and to provide narrow chip spaces for receiving the cut material during the cutting operation. Such noise-reduced tools, at the same blade pitch circle diameter, are heavier than conventional routing tools on account of the greater use of material and can be reground less frequently on account of the small blade projection. In particular in smaller machines of light construction, the large mass of the tool has an adverse effect on the machining quality and on the tool life, which can be attributed to the vibration behavior.
EP 0 688 638 B1 discloses a routing tool having cutting elements which are specifically designed in such a way that they project laterally beyond the router body, thereby enabling rebates and grooves to be machined. The cutting elements are positioned laterally via the inner contour of a channel which is arranged in the seating surface in the cutting element and which is in elastic contact with the lateral surface of a heavy spring pin. Because the cutting element bears against both groove flanks of the trapezoidal groove running continuously over the entire blade height and against the rear surface thereof, the system per se is overdetermined, which is to be compensated for by the heavy spring pin. However, the positioning accuracy suffers due to this configuration, which leads to poor repeatability of the positioning of the blades when fitted repeatedly.